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STSS Demo launch timeline

T-00:00 Liftoff
The Delta 2 rocket's main engine and twin vernier steering thrusters are started moments before launch. The six ground-start strap-on solid rocket motors are ignited at T-0 to begin the mission.
T+01:03.1 Ground SRM Burnout
The six ground-start Alliant TechSystems-built solid rocket motors consume all their propellant and burn out.
T+01:05.5 Air-Lit SRM Ignition
The three remaining solid rocket motors strapped to the Delta 2 rocket's first stage are ignited.
T+01:06.0 Jettison Ground SRMs
The six spent ground-started solid rocket boosters are jettisoned in sets of three to fall into the Atlantic Ocean.
T+02:11.5 Jettison Air-Lit SRMs
Having burned out, the three spent air-started solid rocket boosters are jettisoned toward the Atlantic Ocean.
T+04:23.3 Main Engine Cutoff
After consuming its RP-1 fuel and liquid oxygen, the Pratt & Whitney Rocketdyne RS-27A first stage main engine is shut down. The vernier engines cut off moments later.
T+04:31.3 Stage Separation
The Delta rocket's first stage is separated now, having completed its job. The spent stage will fall into the Atlantic Ocean.
T+04:36.8 Second Stage Ignition
With the stage jettisoned, the rocket's second stage takes over. The Aerojet AJ118-K liquid-fueled engine ignites for the first of two firings needed to place the STSS Demo satellites into the proper orbit.
T+04:41.0 Jettison Payload Fairing
The 10-foot diameter payload fairing that protected the STSS Demo satellites atop the Delta 2 during the atmospheric ascent is jettisoned is two halves.
T+10:32.3 Second Stage Cutoff 1
The second stage engine shuts down to complete its first firing of the launch. The rocket and attached STSS Demo spacecraft are now in a coast period before the second stage reignites. The orbit achieved should be 830 nautical miles at apogee, 100 miles at perigee and inclined 54.6 degrees.
T+42:30.0 Second Stage Restart
Delta's second stage engine reignites for a brief firing that will bring the initial elliptical orbit into a circular one.
T+43:37.0 Second Stage Cutoff 2
The second stage shuts down and completed the powered phase of flight. The circular orbit achieved should be 729 nautical miles high and inclined 58.00 degrees.
T+47:49.0 SV 1 Separation
The upper satellite in the stack of two Space Tracking and Surveillance System spacecraft is released into orbit.
T+55:14.0 SV 2 Separation
The lower satellite in the stack of two Space Tracking and Surveillance System spacecraft is released to complete the launch.

Data source: ULA